When using ADDri to get the address of a stack object, 255 is a conservative

limit on the offset that can be materialized without using the register
scavenger.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106312 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/ARM/ARMBaseRegisterInfo.cpp b/lib/Target/ARM/ARMBaseRegisterInfo.cpp
index c5848d4df8776ed812458c05f1df6a0f694baee1..3cd28b486b43e8241bf3736ef11ba4cf64647d84 100644 (file)
--- a/lib/Target/ARM/ARMBaseRegisterInfo.cpp
+++ b/lib/Target/ARM/ARMBaseRegisterInfo.cpp
@@ -674,6 +674,15 @@ ARMBaseRegisterInfo::estimateRSStackSizeLimit(MachineFunction &MF) const {
          I != E; ++I) {
       for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
         if (!I->getOperand(i).isFI()) continue;
+
+        // When using ADDri to get the address of a stack object, 255 is the
+        // largest offset guaranteed to fit in the immediate offset.
+        if (I->getOpcode() == ARM::ADDri) {
+          Limit = std::min(Limit, (1U << 8) - 1);
+          break;
+        }
+
+        // Otherwise check the addressing mode.
         switch (I->getDesc().TSFlags & ARMII::AddrModeMask) {
         case ARMII::AddrMode3:
         case ARMII::AddrModeT2_i8:

diff --git a/test/CodeGen/ARM/crash-O0.ll b/test/CodeGen/ARM/crash-O0.ll
index 4f0f39fe38ac34e0f400ba05a005d2e14864cdf2..8bce4e0097fa8f96627d7779797348de068ee373 100644 (file)
--- a/test/CodeGen/ARM/crash-O0.ll
+++ b/test/CodeGen/ARM/crash-O0.ll
@@ -10,3 +10,19 @@ entry:
   %asmtmp = call %struct0 asm sideeffect "...", "=&r,=&r,r,Ir,r,~{cc},~{memory}"(i32* undef, i32 undef, i32 1) nounwind ; <%0> [#uses=0]
   unreachable
 }
+
+@.str523 = private constant [256 x i8] c"<Unknown>\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00", align 4 ; <[256 x i8]*> [#uses=1]
+declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
+
+; This function uses the scavenger for an ADDri instruction.
+; ARMBaseRegisterInfo::estimateRSStackSizeLimit must return a 255 limit.
+define arm_apcscc void @scavence_ADDri() nounwind {
+entry:
+  %letter = alloca i8                             ; <i8*> [#uses=0]
+  %prodvers = alloca [256 x i8]                   ; <[256 x i8]*> [#uses=1]
+  %buildver = alloca [256 x i8]                   ; <[256 x i8]*> [#uses=0]
+  call void @llvm.memcpy.p0i8.p0i8.i32(i8* undef, i8* getelementptr inbounds ([256 x i8]* @.str523, i32 0, i32 0), i32 256, i32 1, i1 false)
+  %prodvers2 = bitcast [256 x i8]* %prodvers to i8* ; <i8*> [#uses=1]
+  call void @llvm.memcpy.p0i8.p0i8.i32(i8* %prodvers2, i8* getelementptr inbounds ([256 x i8]* @.str523, i32 0, i32 0), i32 256, i32 1, i1 false)
+  unreachable
+}